Things to consider…
Everything you need to know before getting started
Storage space matters
HRA files are massive, so you need to think in terms of hundreds of gigabytes, not tens. Forget about internal memory: it’s always too little for more than a few songs. Look for devices with MicroSD card slots instead.
Stores are limited
Apple doesn’t currently offer HRA tracks on the iTunes Store or Apple Music, so you’ll need to go elsewhere to obtain them. e-onkyo, 7digital, Technics Tracks and Qobuz are the big ones, and Tidal has some HRA tracks too.
iPhones can do it, sort of
The headphone jack isn’t good enough for HRA – the iPhone 6s’s digital-to-analogue converter goes to 24-bit/48KHz – but you can use the Lightning connector, camera adaptor cable and an HRA app to output in full quality.
Accessories are important
Your audio signal is only as good as your audio accessories: if your headphones prioritise fashion over fidelity then HRA is a waste of your time and money. Just like 4K TV, HRA needs good quality equipment.
You might not need it
Good HRA players can be pricey, and you might get better results by upgrading your existing audio components instead. A better amp or better headphones will often make a bigger difference than a higher sample rate.
The MP3 and AAC formats are inferior to CD, let alone a higher quality master